As a core technology of a next-generation transport network, an optical transport network (OTN) includes technical specifications of an electronic layer and an optical layer, has rich operation, administration and maintenance (OAM) functions, a powerful tandem connection monitoring (TCM) function, and an out-of-band forward error correction (Forward Error Correction, FEC) function, and can implement flexible grooming and management on large-capacity services.
As a rate of a client signal is increasing, a frame in an OTN technology for transmitting the client signal is continuously evolving. Currently, the International Telecommunication Union is discussing a new transmission frame exceeding 100 Gbit/s. However, when such a superspeed transmission frame is used to transmit a service of a relatively low rate, multilevel multiplexing needs to be performed by using an existing low-rate transmission frame, resulting in relatively high complexity and a relatively long delay. On the other hand, if a client signal is carried by directly using a high-rate transmission frame without multilevel multiplexing, there is a problem of low bandwidth utilization.